Repeater-circuit



l G. Cmssoml y REPEATER CIRCUfT. APPLICATION FILED M023, 1918.

IN1A EN TOR.

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' 7 'ATTORNEY ffl misil i i 1 l M i er. n

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GEORGE Caisson, or rroeoKnN, NEW JERSEY, AssrGNoR To AMERrcAN 'rELnrHoNE ann Temeer/irrt COMPANY, A CORPORATION or NEW YonK.

EEPEATER-CIRC UIT.

Specification of Letters Patent. Patented Sept, 2L 192th,

Application filed December 23, 1918. Serial No. 268,072.

7 'o cil/Z 107mm it muy concern lie it known that i, Gnimon siding at Hoboken. in the county of Hudson and 4'itate of New Jersey, have invented certain improvements in Repeater-Circuits, of which the followingis a specification.

This invention relates to repeater circuits and more particularly to means for associating a repeater circuit of either the two'- way tivo-repeater type or of the well-known four-wire type with. terminal two-wire transmission lines.

(')nc of the objects of the invention is the provision or a means for associating a repeater circuit with the terminal two-wire line in snch a manner that the two-wire line shall -be insulated. from the repeater circuit.

Another object of the invention is to providel a connecting arrangement for a repeater circuitv and a terminal line of such character that the terminal line may be phantomed or simplexed without the use of an additional repeating coil.

l@ther and further objects of the invention will appear from the following'description when read in connection with the accompanyingi` drawing, Figure 1 of which .repeater lle.

constitutes a circuit diagram of the preferred embodiment of the invention and YFig. 2 of which is a schematic diagram illustrating certain features of the operation.

Referring to Fig. 1, a repeater circuit including repeaters it, and lig is shown interconnecting terminal two-wire lines L1 and.

L The repeaters Rl and R2 are illustrated as being of mechanical type but itwill be understood -that repeaters of any other type, such as the `,well known vacuum tube repeater, may he employed. The input circuit l() of repeater R1 is connected to the circuit il with i1 is associated through the transformer 12 with the output circuit 13 of ln a similar manner the input circuit 1l of repeater R2 is connected with the circuit 15 which is associated through the transformer 16 with the output circuit 17 of repeater R1. 1n order to associate the repeater circuit with the line L- a transformer is provided having a winding 18 which terminates the line circuit and divided windings 19 and 2O arranged with one-half of each winding in circuits 10 and 11 respectively. TWhere circuits 10 andv 11 are not exposed to external disturbancesone of the windings may be omitted Ciusson, rey In order to balance the line L1 an artificial. line or network, N, is provided, said artificial line being bridged across the junction points 21 and 22 of the circuits 10 and 11. The impedance of this artificial line N1 must have the same phase angle as the impedance of the line L1 but may differ from it in magnitude; The ratio of the impedance of the artificial line N1 to that of the line L1 depends upon the relative number of turns in the windings 18 and 19 and 20. This relation is given by the equation T inz in'` which 7 is ratio of the impedance of the artificial line Nl to the impedance of the line L1 and n is the ratio of the number of turns in winding 18-to the number of turns in windings 19 and-20 together. This requirement may be met by designing the artiicial line N1 tohave the correct impedance, for connection directly to the points 21, 22 but it is usually more convenient to give to the articial line N1 the same impedance, as the line L1 and obtain the correct ratio by means of an auto-transformer 23 inserted between it and the points 21, 22. In the frequently occurring case in. vwhich Athe transformer is designed for equal impedances in the circuits L1, 10, and 11 the ratio of the auto-transformer would be two to one.

In a similar manner the line L2 is associated with the repeater circuit by means of a transformer, including a winding 24 in the line circuit and split windings 25 and 26 in circuits .14C and 15 respectively. An artificial line N2, whichnmay have in circuit therewith auto-transformer 27, is bridged between point 28 and`29 in order to balance the line 2. di!

It will be seen that thetilbove arrangement is such that the output and input circuits of the two repeaters are conductively connected while the repeater circuit as a whole is associated vfith the terminal lines inductively only. The terminal" circuits are therefore insulated from thev repeater circuit and may be phantomed or s implexed by connecting leads 30 and 31 to the inidpoints of windings 18 and'24, Without necessitating the provision of separate phantom or simplex coils.

The arangement above described may be used either for .a two-Way two-repeater circuit or for a four-wire repeater circuit. rThe circuit as shown is that ol' a two-way two-repeater circuit but it the apparatus on each side otl the vertical dotted line y/ be separated and arranged at distant stations, the circuits 1l and l5 being); correspondingly lengthened into a pair of two-wire transmission lines, the arrangement beconies that ol a. tour-wire system.

ln order to more clearly indicate the op eration in transmitting troni line L, to L2, those portions ot' the circuit in which substantially no current flows are indicated by dotted lines The operation is as vfollows:

in alternating telephone current flowing in the line L, will at given instant low in the direction indicated by the arrow to the left of winding` 18. The current thus flowing,` induces potentials in the two halves of windings 19 and 2@ ot such character that currents tend to flow in the directions indicated by the arrows adjacent to halves ot said windings. Assuming that the potentials induced in the two halves of each winding are equal and, that the ilnpedances in circuits l() and l1 are approximately equal, points 2l and 22 will be at substantially the saine potential so that substantially no cur rent ilows through the circuit including the network lll, and the auto-transformer 23.

@n the other hand a current flows in series in the input circuit l0 ot I repeater lll. and the output circuit ll of repeater R2. The energy vdissipated inthe latter circuit is without etiiect Abut the current flowing in the circuit l0 actuates repeater lt, and transinits through the transformer'l a current having' at a given instant the direction indicated by the arrows in circuit l5. tion ot the transitorn'ier, including windings 24.. and 26, is such that this current in tlowing through the lower halves oli' windings 25 and 26 induces an electromotive force in the upper halves ot said windings, said electroniotive torce being,` substantially equal and opposed to the potential difference set up between points 28 and 29 by the current Vflowing` through the impedance ot the artificial line and the auto-transformer 2?, so that substantially no current flows in the input circuit la ot' the repeater lig but substantially the entire current flowing' troni circuit l5 takes a. path through the bridged circuit including the auto-transtormer 2T and balancing network llg. An electrometive torce is induced in the winding 24. whereby a corresponding' current flows to the line ll? ln order to more clearly7 understand the action o" the transformer just described, attention is called to Fig. 2. in which the transl former arrangement is simplified, liet us assume that the impedance ot' the line L2 be represented by Z included in series with the vinding 34 and that the winding- 26 be inytween o and o will be and 26. Consequently there would be 'between these corporated in the winding 253. i assumption is ustitied by reason oi tlthat the winding Q13 is only provi order to balance the two haines otl circo' Llei and l5 respectively, Let the in'ipedancc bridged across the junction, points oit' circuits lilancl l5 be represented in the d grain of Fig. 2 by an impedance Z bride` acrossvpoints o and CZ. 'lhe winding oit the transformer is such that ssuining the action of the transformer to be that of a p" tect transformer, the impedance ot the ci,"m cuit including ini bedance 2i as seen lroin the points o and I) otl the lower halt ol the vinding 25 is equal to impedance Z. it' now the circuit connecting points c and (Z be opened and ay Voltage il be iin pressed between points o and CZ, the voltage drop Y beequal to the Voltar e induced between b and c since both parts the windingn 25 areon the saine core and have the saine number oit turns, Furtheimore, since due to the impedance relations above referred to, the drop between points and is equal tonthat between 'j'ioints i) and d, it follows that the potential dill ence between points 'o and c also equals thaU between points and d. Points o and (Z are4 therefore at the saine potential when a voltage is aoplied between points o and l and consequently no curent will liow through a connection between points df and c vhatover may be the impedance included in such connection. `lt follows, therefore, that in Fig'. l a voltage impressed in the circuit l5 will cause no current How in the circuit il regardless of what may be the impedance ot the latter'circuit. .l

The action above described would in practice only be approximated because the primary current entering the transformer trein circuit l5 contains a component, lknown as the exciting current, which inagnetizes the core and which is not reproduced in winding' 2s. This exciting current` [lowing through the impedance of the artificial line N2 and the auto-transformer 27 causes the potential difference between points 28 and Ztl-to ditler slightly from the electroinotive torce induced in the upper halves ot windings 25 ,rtain amount ot transniissiontrom circuit l5 to circuit lei. lt is possible, however, to compensate for this effect by designing the auto-transformer 27 so that its exciting cus rent is equal to that of the transformer, or by bridging an additional impedance .ineinber across terminals 28 ad 25) so as to provide a suitable path t'or the exciting current points. This would involve making; the open circuit impedance ot the auto-transformer, (or the autotranslormer and impedance mernl'ier in`parallel) equal to one-fourth ot' the inipedamn ot the trans former measured from the cir t with circuit l5 short circuited and thecircnit o'f the line L2 and. the bridged circuit including the auto-transformer 27 and artiiicial line N2 left open.

The action in' transmitting from line L, to line L, is similar to that above described. In this case substantially no current wiii flow in the circuit bridged between points 2S and 29 and substantiallgy no current iiow will occur in the circuit l0;

This repeater circuit would also 'function in substantiallyv the same manner if each line such L, were interchangcd with the corresponding artificial line ril. in this case the current entering` the circuit at points 2l, 22 'from the line L1 would divide into two substantially equal parts which wouldflow in opposite directions in the two halves of 'the windings 19, 20 and consequently would have substantially no effect upon winding` 1 8 and the artificial line N1. ln other respects the action would be unchanged.

lllliile the invention has been disclosed inv what, is believed to be its most desirable Jform, it .will be obvious 'that the general principles thereof may be embodied in many otherl organizations widely different from that'illustrated without departing from the spirit of the invention as "described in the following claims.

1What is claimed is:

l. in mission necting said lines, said repeater' circuit including one-way paths for transmitting in opposite directions, and .means for associating theends of said paths with said transmission lines, said means romprisinaV transformers having` one winding in the transmission lines and divided winc'ngs arranged with one-haii in each path, and balancing; networks bridged. across'thejunction points oi' the paths at the midpoints of the divided windings.

QfIn a telephone system, a transmission line, a repeater circuit associated with said line, said repeater circuit including` one-way paths for transmitting in opposite directions, and meanfsifor associating the ends of said paths, with said line, said means romprising a transformer having one windiint,y in the line and a divided winding' arranged with one-heli` in each path, and a balancing;` network bridged across the junction points ci the paths at the midpoint ,oi the divided winding.

3. In a telephone systeima pair of tranmission lines, a repeater circuit interconnect ing said lines,.said repeater circuit includingry one-wav paths 'for transmitting in oppositefdirections, and means for associating' the ends of said paths with said transmission. lines, said means comprising trans ormers having one winding in 'the transmis a telephone system, a pair of trans-'5 `i lines, a repeater circuit intercom.v

sion lilies and divided windings arranged with one-half in each path, and balancing networks having iinpedances equal tothe line impedances and included in circuits bridged across the junction points of said paths at the midpoints oit the divided windings, said. bridged circuits including transformers whereby the impedance of the balancing networks viewed from the bridging points will have the correct ratio to that of the lines.

a. ln a telephone system, transmission line, a repeater circuit associated.withsaid lh e, said repeater circuit including'onoway paths for transmitting in opposite directions, and means for associatingy the ends of said paths with said line, said means com prisin'g a transformer having one winding in the line and a divided winding arranged with vone-halt in each path, and a balancing networkv having animpedancc equal to the line impedance and included in a circuit bridged across the junction point of said paths at the midpoint oisaid divided winding, said bridged circuit includinga transformer whereby the impedance ot the balancing network as viewed :trom the bridging1 points will have the correct ratio to that of the line.

5. in a telephone system, a pair of trans 9o mission lines, a repeater circuit interconnecting,r said lines, said repeater circuit includ-l ingonaway paths for transmitting in oppo sitedirectiom'and means for associating the ends of said paths with said transmission 111@ lines, said means comprising transformers having' one winding' in the transmissison lines and divided windings arranged with onedialt in each path, balancing networks bridged across the junction points of the lili, paths at the midpoints of the divided windings, and means associated with said. neilwo'rks to compensate for the eiect oi the excitingr current of the transformer.

6. ln a telephone system, a transmission l? line, a repeater circuit associated with said line, said repeater circuit incliiding one wa?,7 paths Jfor transmittingI in opposite di rections, and means for associating the ends of said paths with said line, said means-com- 1 p ising a transformer having one Windin the line and a divided winding arl- 1 ranged with one-halt inA each path, a. balancing network bridged across the junction Apoints ot the paths at the midpoints 12C of the divided winding, and means asso ciated with said network to compensate for the effect of the exciting current of the transformer.

7. in atelephone system, a transmission ma line, a two-way vrepeater circuit. meansv to Vassociate said repeater with said line com .prisma a transformer l'iaving one winding in the transmission line and a divided wind'- ing having one-half in the output vcircuit of '130 one repeaer element A initini* in orosile. directions. a i A he iiipu; circuit of another i Said input and output cizeuis being jaune@ i with said balancing' zitwoi'k 'U2-idg i .i r f thegunctmn pomb iieieof ai; the undp-omis (if the divided wiiidiig'.,

8. )in a te'ifgphoiie system, L 'eperiei" zippa- Iaus including one-way pa'hsl foi' 'maiissnug , and

sion circuit. id :i balancing Gironi 'maals'o assoc/iai@A said circuit@ with the ends of said'pahs, Suid means comprising a i'iulsformer having a divided Winding arranged with one-half in each pmb and. zmotheizwinding arranged in one of said circuits, ii-el other cii'cuit being bridged across the juncion points of tha paths :it the mi hints of the divided Winding.

9. in teifiiom system, pail.' of Tailsl mission cii'cui and :i repeater apparat-us including" two Qcmenps; means to assosiate said repeatei' fippaisiu; wiii said Ci'cuifs Comprising a i'zwsfo'r'mm iiffi'viiig zz divided Winding' arisngsf' Wih one-indi" associated with @zich o 'he of the repeut@ zzppsm-us am. a 56601155 M xaiizig; range@ u1 on@ @i i d mi mnsimsion. circuit mein )filiation poilus *t me midpomts Winding l0* n a eiepimne system in u ai tra nsmi ssisi aphiaiiy distan taf cli-cmi ini l Us said i'apaei cicuijb in@ mie-Way i'uisniission lines i' ting iii opposie diiectioniq, means L: i'

ciatiiig the ends of said (me-Way liu/sr; i is smid emiinai lines, said means compri. k1 tifmiorniei's filming one Winding" in iii@ mimi 51iisi1iissio1i lines and divided wind ings :fzri'angevc'i'w-ith one-hai'f iii cach \ieway line and balancing networks bei across the junction points of the pzifhs lie Vrildponts of the divided windu in es'tinony When-e015, have Si. name i0 thl specification his 5W Y i.' n muy 0i /Qcembei u. 

